1. Field of the Invention
The invention relates to a top element for a convertible top and to a convertible top.
2. Description of Related Art
In current tops of convertibles, especially in folding tops, individual parts of the top linkage, such as the roof rod, control rod, cross bow, front bow, roof tip, main column, main rod or clamp clips are made of metal by punching, deep drawing, diecasting, stretching-bending or forging processes. However, these metal parts have high weight and can form a injury hazard due to splinters in case of a fracture of the part, splintering occurring especially in aluminum and magnesium diecast parts. The metal parts, furthermore, require corrosion protection and cannot be decorated so that separate optical covers are needed. This results in high production costs for a convertible top prepared using these components. In addition, top linkage parts formed especially as single-shell castings have only low bending and torsional stiffness.
An object of the invention is, therefore, to devise a top element for a convertible top which has high strength with low weight and can be produced at comparatively low cost. Another object of the invention is to devise a convertible top which has at least one such top element.
The initially mentioned object is achieved with a top element that is formed from a plastic component and from a sheet metal part as a composite component. One such composite structure enables combination of the advantages of sheet metal with those of plastic and leads to saving of weight with at least the same or even increased bending and torsional stiffness. Moreover, plastic offers the advantage that corrosion protection is not necessary and that the desired colors and surface structures can be considered directly in production.
Increased component strength of the top element is achieved especially in that major areas of the plastic component and the sheet metal part are spaced apart from one another and form a stiff cavity structure. The major areas are established depending on the shape of the component with consideration of the strength requirements and depending on the type of top element can be located at different points of the top element. Preferably, these major spaced areas form most of the plastic component or the entire top element.
When the plastic component and the sheet metal part form a thin-walled composite part with at least one large-volume cavity, an especially light composite part can be formed which still meets high strength requirements. Here, the size of the entire component and especially its extension on the greatest cross section of the cavity are limited solely by the available space for the closed and open convertible top.
Feasibly, the sheet metal part is joined to the plastic component by cementing, clinching or casting, and also any other joining techniques can be used.
The sheet metal part can have been put into the required form, for example, by deep drawing. The sheet metal can be especially thin and, thus, also light since it performs its support function only in an arrangement on the composite part. The plastic component can be produced as an injection molding, deep drawn part or laminated part, thus ensuring great freedom in shaping and also the bearing surfaces necessary for attaching the sheet metal can be optimally shaped.
For the structure of the composite part different arrangements of the sheet metal part and the plastic component can be chosen. Thus, the sheet metal part can form the bottom or inside and the plastic component can form the top or outside of the composite part of the convertible top in its arrangement with the convertible top closed. On the other hand, the plastic component can also form the bottom or inside and the sheet metal part can form the top or outside of the composite part. The arrangement is chosen essentially with consideration of the attachment of decoration and the fracture behavior of the materials being used at the time, such as especially plastic. A high-strength, but splintering plastic is placed on the outside of the top and is covered by sheet metal to the inside towards the passengers.
Preferably, the top element is the front bow of the convertible top, the plastic component being the bottom of the front bow and the sheet metal part being the top of the front bow.
To increase the strength it is feasible if the plastic component of the front bow has an essentially U-shaped cross channel. Additional components such as locks or drives can be accommodated and integrated into this cross channel.
Furthermore, it is feasible if the plastic component has reinforcements and especially stiffening ribs. When the stiffening ribs extend to the roof contour they can be used as bearing and support for the sheet metal part.
Other components can be integrated into the composite part, for example screens, pivots for rods, receivers for locks, catch hooks and the like. Receivers for rocker bearings of rods or guides can be made in the plastic component.
Furthermore, additional sheet metal parts, which can be joined directly to the sheet metal part, can be inserted or integrated in the plastic component.
For the plastic component different plastics such as polyamide (PA6.6) can be used, the plastic component being formed especially from a plastic with an essentially splinter-free fracture behavior if it is pointed towards the vehicle interior.
Feasibly, a top linkage part, such as especially a roof rod, a control rod, a main column, a cross bow, a front bow or a roof tip or a part combined from at least two of these linkage parts can be feasibly used as the top element, here the advantages of the composite construction with a plastic component having an especially positive benefit as a result of the freedom of configuration.
The second object is achieved in that the convertible top has at least one top element which is made as a composite part which is produced from a combination of a sheet metal part with a plastic component. Feasibly, the top element is made according to the aforementioned details and is especially a roof rod, a control rod, a main column, a cross bow, a front bow or a roof tip.
These and further objects, features and advantages of the present invention will become apparent from the following description when taken in connection with the accompanying drawings which, for purposes of illustration only, show several embodiments in accordance with the present invention.